title: The purinergic component of human bladder smooth muscle cells' proliferation and contraction under physiological stretch.
abstract: OBJECTIVE
  To investigate whether cyclic stretch induces proliferation and contraction of human smooth muscle cells (HBSMCs), mediated by P2X purinoceptor 1 and 2 and the signal transduction mechanisms of this process.
  
  
  METHODS
  HBSMCs were seeded on silicone membrane and stretched under varying parameters; (equibiaxial elongation: 2.5%, 5%, 10%, 15%, 20%, 25%), (Frequency: 0.05Hz, 0.1Hz, 0.2Hz, 0.5Hz, 1Hz). 5-Bromo-2-deoxyuridine assay was employed for proliferative studies. Contractility of the cells was determined using collagen gel contraction assay. After optimal physiological stretch was established; P2X1 and P2X2 were analyzed by real time polymerase chain reaction and Western Blot. Specificity of purinoceptors was maintained by employing specific inhibitors; (NF023 for P2X1, and A317491for P2X2), in some experiments.
  
  
  RESULTS
  Optimum proliferation and contractility were observed at 5% and 10% equibiaxial stretching respectively, applied at a frequency of 0.1Hz; At 5% stretch, proliferation increased from 0.837±0.026 (control) to 1.462±0.023%, p<0.05. Mean contraction at 10% stretching increased from 31.7±2.3%, (control) to 78.28 ±1.45%, p< 0.05. Expression of P2X1 and P2X2 was upregulated after application of stretch. Inhibition had effects on proliferation (1.232±0.051, p<0.05 NF023) and (1.302±0.021, p<0.05 A314791) while contractility was markedly reduced (68.24±2.31, p<0.05 NF023) and (73.2±2.87, p<0.05 A314791). These findings shows that mechanical stretch can promote magnitude-dependent proliferative and contractile modulation of HBSMCs in vitro, and P2X1 and 2 are at least partially responsible in this process.
authors.affiliation: Department of Urology, West China Hospital, Sichuan University, Chengdu, Sichuan, PR China.
authors.forename: Romel
authors.initials: R
authors.lastname: Wazir
authors.forename: De-Yi
authors.initials: DY
authors.lastname: Luo
authors.forename: Ye
authors.initials: Y
authors.lastname: Tian
authors.forename: Xuan
authors.initials: X
authors.lastname: Yue
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Kun-Jie
authors.initials: KJ
authors.lastname: Wang
mesh_terms: D001483:Base Sequence; D049109:Cell Proliferation; D002478:Cells, Cultured; D017931:DNA Primers; D006801:Humans; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D011983:Receptors, Purinergic / Q000378:metabolism*; D001743:Urinary Bladder / Q000166:cytology / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D011983:Receptors, Purinergic
keywords: Bladder smooth muscle cell; Contractility; P2X1; P2X2; Proliferation; Stretch